This invention relates to sensors or switches which utilize the fact that gravity will maintain an unrestricted conductive contact element, such as a metal ball or ball of liquid mercury, in the lowermost position relative to its containment chamber to indicate attitudinal position of the switch or sensor relative to true vertical, and correspondingly the attitudinal position of any object attached thereto. More particularly, the invention is a sensor which is able to monitor the attitudinal position of an object relative to true vertical over a three axis pathway, such that a single sensor can monitor the movement over the pathway even if the object and sensor are inverted or tilted in any plane, and regardless of whether the object is fixed in space or moved positionally. Even more particularly, the invention relates to such a sensor having a sensing pathway defined on all or part of a spherical or multiply curved surface.
There are many situations where it is necessary or desired to monitor or sense the attitudinal position of an object relative to true vertical. Switches or sensors which utilize the effect of gravity on a ball of liquid mercury or an electrically conductive metal ball or roller are well known, the switch being designed such that the unrestricted conductive member makes or loses contact with a pair of leads in an electrical circuit dependent on the attitude of the switch relative to true horizontal, such that contact with the leads or loss of contact with the leads which occurs when the attitudinal position of the switch is altered relative to vertical results in a signal or other electrical action occurring. Such switches or sensors are commonly referred to as mercury or gravity switches. Such simple gravity switches work when the object or switch is rotated about a non-vertical line, such that the switch is activated or deactivated when a particular angle relative to vertical is exceeded and gravity causes movement of the conducting ball away from or against the contact leads. In order to track attitudinal positioning of an object along various curved pathways in the X-Y-Z three axis world, where the switch is rotated, tilted and/or inverted, the known solution is to attempt to combine a number of such two dimensional switches. Any such solution, especially when the object is inverted, requires determination of sequential activation and deactivation scenarios, since certain of the switches will be non-functional or provide incorrect signals when the object passes through various positions relative to vertical.
It is an object of this invention to provide a single gravity-type sensor switch which monitors the position of an object over a three dimensional pathway which extends dimensionally about all three axes where the object may be tilted, rotated or inverted, as well as translated through space rather than focused on a fixed location, so as to provide a signal to indicate that the object is moving in the correct three dimensional manner. It is a further object to provide such a switch which contains a gravity controlled contact member which remains at the bottom of the sensor because of gravity as the position of the sensor changes relative to true vertical, where the sensor comprises a curved contact pathway corresponding to the desired three dimensional movement path of the object, where the contact member is contained within a curved tube or a pair of matching curved surfaces which can be part or all of a sphere, a combination of multiple curved surfaces or of any three dimensional curvilinear pathway in space.